When you’re five miles down a trail, even a small blister or wood splinter can become a big, painful problem.

A well-stocked first-aid kit could save the day, but many hikers don’t even bother to bring a single bandage, says Julie Anderson, who works as a backcountry paramedic and an instructor with Wilderness Medical Associates International in Alaska.

“A lot of people buy premade kits, but those are so bulky that they often get left at home,” she says. Her advice: Make your own light, useful kit.

Start with bandages and pieces of sterile gauze in several different sizes. Athletic tape can prevent blisters, protect wounds, or stabilize a sprained ankle. Anderson also brings along pain relievers, a small tube of antibiotic gel, sharp-pointed tweezers, and latex-free gloves to keep any splinter surgeries germfree.

Sunblock, a multitool, and a small flashlight can also come in handy, but take it easy. Ideally, a kit for a day hike weighs around six ounces, Anderson says. That’s about as heavy as your smartphone—and you can always make room for that.

This article was first published in May 2014. Some facts may have aged gracelessly. Please call ahead to verify information.